Q: What type of adapter do you put the sd cards in?

I'm updating from an ipad 3rd Gen to an air 2.  What type of adapter do you put the sd cards in with an air 2? With my older ipad I used an apple sd card reader that plugged into the 30 pin. I purchased an sd reader for the 8 pin ipad 4th Gen that my wife has and it wouldn't work. I use my ipad for hundreds of photos, all 8 digits and DCIM. Thanks for any help.